Trioctylphosphine oxide-impregnated hollow fiber membranes for removal of phenol from wastewater

Trioctylphosphine oxide (TOPO) was immobilized in polypropylene hollow fiber membranes for removal of phenol from wastewater. Scanning electron microscopy showed white deposits of TOPO dispersed non-uniformly within the resulting extractant-impregnated hollow fiber membranes (EIHFM). The EIHFMs manifested high adsorption capacity and mass transfer rates, with adsorption equilibrium attained within 10–30 min of operation. Experimental equilibrium adsorption capacities with a feed of 1000 mg/L phenol were 32, 42, 52 and 57 mg/g at 50, 100, 200 and 400 g/L TOPO, respectively. During repeated operation with 1000 mg/L phenol, the adsorption capacities of the EIHFMs remained stable at 32.2±1.3 and 52.3±0.9 mg/g for 10 subsequent runs at TOPO concentrations of 50 and 100 g/L, respectively. The EIHFMs, when used as adsorbents in a two phase partitioning bioreactor, alleviated substrate inhibition on Pseudomonas putida by rapidly adsorbing phenol to sub-inhibitory levels. Biodegradation of 1000 and 2000 mg/L phenol was completed within 26 and 36 h, respectively. These results suggest that the EIHFM is a promising technology for solventless extraction of aromatic compounds in wastewater treatment.